It is the intent of this proposal to examine neural activity in the geniculate ganglion during NA-appetite induced by differing regimens. In the regimen A, animals will be maintained on a 1% (NA-replete) or a NA- deplete diet for 10-14 days prior to the electrophysiological recordings. Regimen B will consist of a sodium depletion induced with the diuretic flurosemide (5.0 mg/1.0 ml, i.p.). Electrophysiological recordings from the somata of individual neurons of the geniculate ganglion will be made while stimulating the anterior tongue or nasoincisor ducts of the palate with NaC1. Sodium appetite is an innate motivatikonal system similar to hunger and thirst, but with the unique characteristic that its adequate stimulus is a single ion -- Na+ -- that is detected in the environment by a single sensory system, taste. Although the neural mechanisms that control sodium appetite are unknown, prior research has revealed that inducing a sodium appetite actually alters the way the gustatory system responds to sodium. These changes may contribute to the characteristic behavior of salt appetite, i.e. ingesting large quantities of concentrated sodium. The results of these prior experiments, however, are inconsistent with one another, perhaps because they used different preparations and examined different levels of the nervous system. The current experiments will eliminate these methodological differences and by obtaining data from peripheral gustatory neurons, establish whether different procedures for inducing a salt appetite alter taste coding at the first level of neural processing.